star Michael Dorn has been tapped for the juicy recurring role, TVGuide.com has learned exclusively. The erstwhile Lt. Commander Worf will first appear in the Season 4 premiere, and at least one other episode, according to executive producer Laurie Zaks, who says Beckett's time on the shrink's couch may also hold some key answers about the evolution of Beckett's relationship with Castle (Nathan Fillion).

"It's going to dredge up a whole bunch of stuff," Zaks says. "Her conversations will enlighten how the relationship will move forward to whatever that next level is."

The therapy sessions may also help Beckett finally get some closure with her mother's murder, the investigation of which has put Beckett into her current life-threatening predicament. "I think Beckett knows that in order to move on with her life she is going to have either let go or deal with how her mother died," Zaks says.

The therapist may not be the only one to whom Beckett pours her heart out. Katic tells us the show may be introducing a close friend of Beckett's."We see Castle in the loft, and he's very vulnerable to his family members. So, we see a lot of the inter-workings of his end of the love story," Katic says. "I don't think we really know what's going on in Beckett's world, so it's time to kind of to open that up. ... [We've] talked a bit about potentially bringing in a friend or some kind of intimate character that can open up the other sides of her too."But how will the hard-charging Beckett respond to Dorn's headshrinker? "She's savvy enough to get through [the therapy] and then realizes that it's something that is kind of a slow-burning medicine," Katic says. It's one of those things that you hate to do, but you have to in order to get better."Castle returns Monday, Sept. 19 at 10/9c on ABC.